Endocardial Implantation of a Cardioverter-Defibrillator in a 13-Month-Old Child Affected by Long-QT Syndrome and Syndactyly

Genetics of ion-channel disorders

PURPOSE OF REVIEW

In this article, we summarize the main features of the most common inherited channelopathies, focusing on the findings that advanced the field in the last few years.

RECENT FINDINGS

The progress in genetics prompted the discovery of several new genes associated with ion-channel disorders, elucidating new molecular pathways and new arrhythmogenic mechanisms. The diffusion and availability of genetic screening gave a new relevance to the application of genetics not only for diagnosis, but also for risk assessment and therapeutic decisions. As a consequence, the present challenge in the field is represented by the need to use genetic data to develop personalized clinical approaches.

SUMMARY

Over a few years, the field of inherited arrhythmogenic diseases has rapidly expanded, thus reshaping clinical management for these conditions. It is now clear that to handle these patients a specialized expertise is needed, able to translate the discoveries derived from basic science studies into the clinical care of the patients.

A successfully novel ICD implantation and medical treatment in a child with LQT syndrome and self-limiting ventricular fibrillation

Beta-blocker is the first line drug therapy for congenital long QT syndrome. However, in some children this drug is ineffective. In a non-responder patient, Shimizu et al. used Mexiletine to suppress the ventricular arrhythmias, obtaining a good result. In the high risk patient, the ICD is necessary. However the implantation of a device in small children can have technical problems. We report a case of a child affected by long QT syndrome with recurrent episodes of syncope due to self-limiting torsade de point/ventricular fibrillation, successfully treated by an association of mexiletin and propanolol, and in whom an ICD was implanted with a new subcutaneous approach.

Monomorphic Ventricular Tachycardia Due to Brugada Syndrome Successfully Treated by Hydroquinidine Therapy in a 3-Year-Old Child

Mutations in the SCN5A gene can cause Brugada syndrome, a genetically inherited form of idiopathic ventricular fibrillation. We describe the case of a 3-year-old child with a structurally normal heart presenting with monomorphic ventricular tachycardia. Her electrocardiogram suggested a Brugada syndrome and the diagnosis was confirmed by the identification of a Brugada syndrome in her mother and in two other family members. Genetic study led to the identification of a c.2516T-->C SCN5A mutation. The child was treated with quinidine therapy without recurrence of arrhythmic events for a time period of 16 months.

Endocardial Implantation of a Cardioverter Defibrillator in Early Childhood

INTRODUCTION

Experience in endovascular/endocardial techniques for implanting implantable cardioverter defibrillators in early childhood is limited. Potentially, this type of approach could limit the surgical risk, while increasing ICD therapy efficacy. The safety and feasibility of adopting a complete endovascular/endocardial approach for implanting ICDs is assessed by considering the cases of two young children.

METHODS AND RESULTS

Two boys, aged 3 and 6 years, were implanted with ICD for a history of syncope and documented ventricular tachycardia (VT). A complete endovascular/endocardial approach was adopted consisting of positioning a bipolar pacing and sensing lead in the right ventricular (RV) apex with intravascular redundancy forming a loop in the inferior vena cava (IVC), and a caval coil placed in the IVC. Sensing values (7-8 mV), pacing threshold (0.5-0.6 V/0.5 msec), and defibrillation testing (case 1 = 10 J, case 2 = 20 J) were all acceptable. During follow-up, in both cases ICD intervened correctly. In one case, 16 months after implantation, because of change in the IVC coil-active can vector, the IVC coil was effectively repositioned to a more distal position.

CONCLUSION

A complete endovascular/endocardial ICD implantation technique in early childhood is both feasible and safe. This approach avoids thoracotomy and ensures ICD therapy efficacy.